The present disclosure relates to disk brake caliper pistons and piston systems, such as are used for various vehicles including automobiles, trucks, aircraft and the like. Embodiments of the disclosure include pistons having provision for an oversized bearing surface for contacting a brake pad, retraction systems for retracting the portions of the piston and/or sealing systems internal to the piston.
As vehicles are made larger and heavier, greater braking force can be helpful in stopping the vehicle. Increased braking force can be accomplished in a number of ways, such as by pushing harder on the brake pedal, increasing the hydraulic advantage within the braking system to achieve greater pressure at the brake piston, increasing the number of brake pistons to increase the brake force achieved for a given hydraulic pressure or to increase the diameter of the piston to increase the brake force achieved for a given hydraulic pressure.
Increasing the number of pistons can result in problems with implementing a parking brake system integrated with the brake piston. The reason for this can include that the spindle/nut arrangement, shown for example in FIG. 5b, should be implemented on both pistons associated with a wheel or risk uneven wear and/or uneven application of brakes which can lead to other operational problems such as binding of the piston.
However, simply increasing the diameter of the piston is limited by the width of the brake pad.
In addition, increasing the pressure that the piston operates at to increase the force also carries a risk of distorting the brake pad due to the presence of a highly localized force (at the piston), which can also lead to uneven wear and other operational problems.